Conveying roller, production method thereof and conveying apparatus

ABSTRACT

A conveying roller pair disposed in a bleaching-fixing bath of a photographic printer is constituted of a flat roller and a projection roller. Plural roller pieces are fixed to a roller shaft of the projection roller. Plural projections are formed by coating molding on an outer peripheral surface of the roller piece. Each roller piece has a core with an approximately ring shape, and an elastic layer with plural projections. The core and the elastic layer are adhered through a primer layer. Accordingly, uniform adhesive strength is secured and slipping of the elastic layer on the core is prevented. Since the plural projections are arranged in a phase-coherent manner, contact condition and contact pressure between the sheet and the projection roller are kept constant. As a result, a skew of the sheet is prevented.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a conveying roller having plural projections on an outer peripheral surface thereof, a method for producing the conveying roller and a conveying apparatus using the conveying roller.

2. Background Arts

For example, a photographic printer performs processes of exposing, developing, drying and the like in this order to a photosensitive recording paper of a cut-sheet type while conveying in a sub-scanning direction. The photosensitive recording paper is nipped and conveyed by a plurality of conveying roller pairs disposed along a passage. Because of the restrictions such as a printer size and the like, the passage is curved in up-and-down directions in several sections in the printer, particularly in a processing tank in which a processing solution for developing is stored. For that reason, the plurality of conveying roller pairs are placed in the processing tank at narrow intervals.

When the conveying roller is constituted of flat rollers, the photosensitive recording paper is frequently squeezed by the flat rollers. As a result, the quality in edge portions of the photosensitive recording paper may be deteriorated. Further, when the photosensitive recording paper is nipped by one side of the conveying roller pair in a width direction, a roll alignment may be changed. Accordingly, a conveying force becomes unbalanced in the width direction so that the photosensitive recording paper may be skewed. In order to prevent such problems, the conveying roller pair disposed in the processing tank is usually constituted of a projection roller, which has plural projections on an outer peripheral surface thereof, and the flat roller (see page 4 of Japanese Patent Laid-Open Publication No. 2001-106376).

The projection roller is usually formed by inserting a cylindrical core, which is made of metal or resin, into a silicone rubber tube whose outer peripheral surface is formed with plural projections. An external diameter of the core is larger than an internal diameter of the silicone rubber tube. In that case, slipping of the silicone rubber tube against the core is prevented by a tightening force of the rubber tube alone. Further, there is a known method for producing the projection roller, in which a rubber roller is inserted into a tube, and the outer peripheral surface of the rubber roller and the tube are adhered with using a primer (see page 3 of Japanese Patent Laid-Open Publication No. 5-147125). Furthermore, instead of using the primer, there is a method in which the core and a rubber layer are directly adhered through chemical bonding between a vulcanized rubber and a thermoplastic resin by forming the rubber layer made of the vulcanized rubber on the outer peripheral surface of the core made of the thermoplastic resin.

When producing the projection roller using the above methods, a width of the rubber tube with the projection is usually formed longer than the width of the passage. However, in that case, an outer diameter of the projection tube tends to vary in the width direction. As a result, contact condition and contact pressure between the photosensitive recording paper and the projections of the projection roller vary in the width direction, which may generate the skew of the photosensitive recording paper. In order to prevent such problems, the projection roller is formed by attaching plural projection tubes to the core (see page 4 of Japanese Patent Laid-Open Publication No. 2001-106376). Thereby, phases of the projections formed in adjacent projection tubes are shifted so that arrangements of the projections become random. Accordingly, the variations in the outer diameter of the projection tube are virtually canceled.

When the projection roller, which prevents the slipping of the projection tube only by the tightening force thereof, is used, the tightening force of the projection tube is down by a slight swelling of the projection tube in the processing solution, or the stress relaxation of the projection tube itself. In particular, since the projection roller is soaked in the processing solution for a long time, the projection tube is swelled to a certain extent even if the projection tube is formed of a chemical-resistant material. Especially in the developing solution, the problems such as the slipping of the projection tube and failures in conveying the photosensitive recording paper tend to increase as the tightening force of the projection tube is down by the swelling. Further, since the projection roller nips and conveys the photosensitive recording paper with a high conveying force while deforming the projections formed on the outer peripheral surface thereof, the stress is concentrated at the projections. As a result, the stress applied to the projections during the conveyance accelerates the expansion of the projection tube which causes stress relaxation. Accordingly, the slipping occurs easily.

Inserting the core into the projection tube is troublesome since the core should be inserted while expanding the projection tube. Further, when inserting the core into the projection tube, there may be a gap between the core and the projection tube, or a distortion on the projection tube. As a result, the position of each projection may deviate from the designed position, or the outer diameter of each projection tube may vary. Furthermore, an edge of the core may tear the projection tube when inserting the core into the projection tube.

When plural projection tubes are attached to the outer peripheral surface of the core, the variations in the outer diameter of the projection tube are canceled as the phase of the projection arrangement is shifted in each projection tube (see page 4 of Japanese Patent Laid-Open Publication No. 2001-106376). However, in that case, a leading end of the photosensitive recording paper may be curled and damaged, and projection marks may be caused by the projections deforming the recording paper in the leading end, since a part of the leading end of the recording paper may enter between the rollers at a large entry angle with respect to the projections. Further, since the contact condition and the contact pressure between the photosensitive recording paper and the projection roller cannot be kept constant throughout the width direction, the skew of the photosensitive recording paper cannot be prevented.

To solve such problems, there is a method in which the projection tubes are attached to the core such that each projection is aligned in the same phase. However, it is difficult to manually set each projection in the same phase. Further, note that the page 4 of Japanese Patent Laid-Open Publication No. 2001-18328 does not disclose a method for performing phase alignment of each projection when forming the vulcanized rubber layer on the outer peripheral surface of the core made of the thermoplastic resin. Furthermore, the core made of the thermoplastic resin is usually formed by injection molding using a mold. At that time, gas generated during the injection molding may be deposited on the surface of the core depending on deterioration of the mold with time lapse and the type of the material used for the injection molding. As a result, the deposited gas may weaken the chemical bond between the resin and the vulcanized rubber when the vulcanized rubber layer is formed on the outer peripheral surface of the core made of thermoplastic resin. Accordingly, there is a possibility that required level of the adhesive strength is not obtained.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a conveying roller, a production method thereof and a conveying apparatus which prevent failures in conveying by preventing slipping of an elastic layer around an outer peripheral surface of the core.

Another object of the present invention is to provide a conveying roller, a production method thereof and a conveying apparatus which prevent the failures in conveying by keeping contact condition and contact pressure constant between a sheet and the conveying roller.

In order to achieve the above and other object of the present invention, an elastic layer with plural projections of the same phase is formed by coating molding on an outer peripheral surface of a core. A conveying roller includes a roller shaft and plural cores fixed to the roller shaft such that the cores and the roller shaft integrally rotate about a rotation center line of the roller shaft. The elastic layer with plural projections is formed on the outer peripheral surface of each core after a primer layer is formed on the core. The core and the elastic layer are adhered through the primer layer. Before forming the primer layer, it is preferable to perform blasting to the surface of the core for increasing adhesive strength.

Further, the plural projections are aligned to form projection lines, which are parallel to the rotation center line, and the projection lines are arranged at a constant pitch in a circumferential direction. The adjacent projection lines in the circumferential direction are shifted in the direction of the rotation center line and arranged in a zigzag. Further, a fitting hole is formed through the core along the rotation center line, and the plural cores are attached to the roller shaft by inserting the roller shaft into the fitting hole. It is preferable to attach a fixing member to the roller shaft and form an engaging section in each core for fixing each core to the roller shaft by engaging the fixing member in the engaging section.

In a method for producing the conveying roller of the present invention, the elastic layer with plural projections is formed by coating molding on the outer peripheral surface of the core. The plural cores formed with the elastic layer are fixed to the roller shaft such that the plural cores and the roller shaft integrally rotate about the rotation center line of the roller shaft. The coating molding of the elastic layer is performed by setting the core as a core in the in a mold, and filling an elastic material in a cavity formed between the core and the mold. The core is set in the mold in a predetermined position in the circumferential direction.

The core is formed of a thermoplastic resin material, a thermosetting resin material or a metal material. The elastic layer is preferably formed of a vulcanized rubber or a thermoplastic elastomer. It is preferable that the hardness is approximately 50 degrees.

A conveying apparatus of the present invention includes a conveying roller pair. The conveying roller pair includes the conveying roller and a flat roller used in a pair with the conveying roller for nipping and conveying the sheet. Further, it is preferable that the projections in a nip area, where the sheet is nipped, are deformed so that the projections outside the nip area in a width direction of the conveying roller contact the flat roller when the conveying roller and the flat roller nip the sheet. Furthermore, it is preferable to use a photosensitive material as the sheet. The conveying roller pair is preferably disposed in a storage tank in which processing solution is stored. It is preferable that the elastic layer, the core and the primer layer are chemical-resistant to the processing solution.

The conveying roller, a production method thereof and a conveying apparatus using the conveying roller prevents the slipping of the elastic layer on the outer peripheral surface of the core while conveying the sheet, since the elastic layer with the plural projections is formed by coating molding on the core. As a result, the failures in conveying the sheet is prevented. Further, although the number of the processes for producing the conveying roller is increased by forming the elastic layer, the working efficiency is substantially improved as the processes for inserting the core into the projection tube become unnecessary. Furthermore, the core is no longer inserted into the projection tube by manual work. Accordingly, yields in manufacturing the projection roller and the quality stability are improved at the same time.

The entry angle of the sheet can be kept constant throughout the leading end of the sheet while the sheet enters between the conveying roller and the flat roller which form the conveying roller pair. As a result, it becomes possible to prevent the projection marks which are caused by the projections pressing the part of the sheet. Further, the contact condition and the contact pressure can be kept constant throughout the width section of the sheet. Accordingly, the skew of the sheet is prevented by preventing unbalance in the conveying force of the conveying roller and changes in the roll alignment.

Further, since the core and the elastic layer are adhered through the primer layer, the uniform adhesive strength is secured regardless of the surface profile in the core.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and advantages of the present invention will become apparent from the following detailed descriptions of the preferred embodiments when read in association with the accompanying drawings, which are given by way of illustration only and thus do not limit the present invention. In the drawings, the same reference numerals designate like or corresponding parts throughout the several views, and wherein:

FIG. 1 is a schematic view of a photographic printing system;

FIG. 2 shows a conveying roller pair disposed in a bleaching-fixing bath in a processor section;

FIG. 3 is a lateral view of a core constituting a projection roller of the conveying roller pair;

FIG. 4 is a front view of the core;

FIG. 5 is a cross-sectional view of the core viewed from a lateral side;

FIG. 6 is a cross-sectional view of a mold for coating molding of an elastic layer on an outer peripheral surface of the core;

FIGS. 7A, 7B and 7C are explanatory views showing steps for attaching roller pieces to a roller shaft of the projection roller: FIG. 7A shows a cross-sectional view of the projection roller when the first roller piece is attached, FIG. 7B shows a cross-sectional view of the projection roller when the second roller piece is attached and FIG. 7C is a cross-sectional view of the projection roller when all the roller pieces are attached;

FIG. 8A is a cross-sectional view of the roller shaft which has a D-cut section, and FIG. 8B is a front view of the roller piece whose fitting hole is formed in a D-shape;

FIGS. 9A and 9B are explanatory views showing steps for attaching the roller pieces of FIG. 8B to the roller shaft of FIG. 8A: FIG. 9A is a cross-sectional view of the roller shaft when the first roller piece is attached, and FIG. 9B is a cross-sectional view when the second roller piece is attached;

FIG. 10A is a cross-sectional view of the roller shaft to which a key is attached, and FIG. 10B is a front view of the roller piece, an opening of which is formed with a key groove;

FIGS. 11A and 11B are explanatory views showing steps for attaching the roller pieces of FIG. 10B to the roller shaft of the FIG. 10A: FIG. 11A is a cross-sectional view when the first roller piece is attached, and FIG. 11B is a cross-sectional view when the second roller piece is attached; and

FIGS. 12A and 12B are explanatory views showing steps for attaching the roller pieces, each of which has concave and convex sections in the core, to the roller shaft: FIG. 12A shows the beginning of attaching the roller pieces, and FIG. 12B shows when all the roller pieces are attached.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As shown in FIG. 1, a photographic printing system 10 is an image output apparatus which is constituted of an image input device 11, an image processing device 12, a printer 13, a processor 14 and the like. Each section of the photographic system 10 is connected to a controller 15 through wiring (not shown). The controller 15 controls the overall operation of the photographic system 10.

The image input device 11 generates image data by photoelectrically reading an image recorded on a photographic film by using an image capture device such as a CCD image sensor, or obtains the image data by reading the image data recorded in a recording medium such as a memory card, CDR, DVD-R and the like. The image data is sent to the image processing device 12, and image processing such as color balance correction and density correction are performed to the image data. After the image processing, the image data is sent to the printer 13.

The printer 13 records images on a photosensitive recording paper (a recording material), which is cut in a predetermined length, using recording light whose intensity is modified according to the image data, while conveying the photosensitive recording paper in a sub-scanning direction (a conveying direction). The printer 13 is provided with a supply section 17, a back-printing section 18, a skew-correcting section 19, an exposure section (image recording section) 20, a receiver section 21, a sorter section 22, a carrying section 23 and the like in this order from an upstream. In each of the above sections, plural conveying roller pairs, each of which is constituted of a drive roller and a nip roller, are disposed along a main passage 24 (indicated by an alternate long and short dash line in FIG. 1) of the photosensitive recording paper.

In the supply section 17, magazines 27 a and 27 b are set. Each of the magazines 27 a and 27 b contains a recording-paper roll 26 which is a photosensitive recording paper 25 in a roll form. In the magazines 27 a and 27 b, paper roller pair 28 a and 28 b are disposed respectively for pulling out and conveying the photosensitive recording paper 25 toward the back-printing section 18. When the paper roller pair 28 a and 28 b are rotated by a paper feed motor (not shown), the photosensitive recording paper 25 is pulled out from the recording-paper roll 26 and conveyed toward cutters 30 a and 30 b. The cutters 30 a and 30 b cut the photosensitive recording paper 25, which is pulled out for a predetermined length in accordance with the print size, to form a paper sheet 35.

In the embodiment, since the paper sheet 35 is conveyed in a single line to the sorter section 22, which will be described later, timing of supplying the paper sheet 35 from each of the magazines 27 a and 27 b is automatically adjusted. Further, when the magazines 27 a and 27 b contain the same type of the photosensitive recording paper 25 (the recording-paper roll 26), the photosensitive recording paper 25 may be pulled out from one of the magazines (27 a or 27 b) first, and then from the other magazine after the photosensitive recording paper 25 is completely pulled out from the initially selected magazine. The plural conveying roller pairs disposed along the main passage 24 convey the paper sheet 35, which has been cut by the cutters 30 a and 30 b, through the back-printing section 18, the skew-correcting section 19, the exposure section 20, the receiver section 21, the sorter section 22 and the carrying section 23 in this order.

The back-printing section 18 has a back-printing head 37 which records print information, such as a photography date, a print date, a frame number, various IDs and the like, on the back (an opposite side of the recording surface) of the paper sheet 35.

The skew-correcting section 19 is constituted of a resist roller pair 39 and the plural conveying roller pairs disposed at the front and rear of the resist roller pair 39. The resist roller pair 39 corrects an inclination of the paper sheet 35 so as to prevent misalignments in an angle and an exposure position of the paper sheet 35 in the exposure section 20. Any known methods can be used for correcting the skew using the resist roller pair 39. For instance, the methods disclosed in Japanese Patent Laid-Open Publication Nos. 4,602,778 and No. 11-349191 can be applied.

The exposure unit 20 is constituted of an exposure unit 41, feed roller pairs 42 and 43, and the like. The exposure unit 41 includes a known laser printer and an image memory (not shown). In the image memory, image data sent from the image processing device 12 is stored. The laser printer exposes the image on the paper sheet 35 by scanning the recording light (the laser light), which is modulated according to the image to be recorded, in a main-scanning direction perpendicular to the sub-scanning direction. Nip rollers of the feed roller pairs 42 and 43 are switchable between a nip position, in which the paper sheet 35 is nipped, and a release position in which the paper sheet 35 is released. The nip position and the release position of each nip roller are switched when a position sensor (not shown) detects a leading end or a trailing end of the paper sheet 35. Thereby, it becomes possible to prevent velocity fluctuations in conveying the paper sheet 35 during the exposure.

The receiver section 21 has plural roller pairs for retaining a leading end of the paper sheet 35 which is conveyed from the exposure section 20 after the exposure, and conveys the paper sheet 35 toward the downstream in the conveying direction with the same velocity as that in the exposure section 20. Each roller pair in the receiver section 21 is constituted of a drive roller and a nip roller which is releasable. The nip roller releases the paper sheet 35 during the exposure. When the exposure of the trailing end of the paper sheet 35 is completed, the nip roller moves to the nip position, and nips and conveys the paper sheet 35 to the sorter section 22.

The sorter section 22 sorts the paper sheet 35, which has been conveyed in the single line, into plural lines according to the sheet size while conveying the paper sheet 35 at a predetermined first velocity. For instance, when the paper sheet 35 is of a normal or small size, the sorter section 22 sorts the paper sheet 35 into two lines. When the paper sheet 35 is of a large size, which cannot be conveyed in parallel, the sorter section 22 conveys the paper sheet 35 in the single line without sorting. The carrying section 23 conveys the paper sheet 35, which is conveyed from the sorter section 22, to the processor 14 at a second velocity corresponding to a processing speed of the processor 14.

The processor 14 is constituted of a processing section 46, a drying section 47, a passage changing section 48, a rearranging section 49, a sorter 50 and the like. The paper sheet 35 conveyed from the printer 13 is conveyed in parallel in the processor 14 along the main passage 24 indicated by the alternate long and short dash line in FIG. 1.

In the processing section 46, a developing bath 52, a bleaching-fixing bath 53 and a washing bath 54 are disposed in this order from the upstream. Predetermined amounts of a developing solution 52 a, a bleaching-fixing solution 53 a and a washing solution 54 a are stored in the developing bath 52, the bleaching-fixing bath 53 and the washing bath 54 respectively. In each bath 52, 53 and 54, a paper conveying rack 55 is loaded. In each paper conveying rack 55, plural conveying roller pairs 58 are disposed at predetermined intervals. The conveying roller pair 58 is constituted of a flat roller 56 and a projection roller 57 which will be described later. To make a photographic print, the paper sheet 35 is sequentially conveyed in parallel through each bath 52-54 by the conveying roller pair 58 for developing, fixing and washing. When there is a possibility that the projection roller 57 may cause unevenness in developing, the projection roller 57 can be replaced with a flat roller of the same size.

The drying section 47 is disposed in an upper section of each bath 52-54, and is constituted of a belt and a ventilation duct (not shown). The ventilation duct supplies dry air heated by a heater (not shown) to the paper sheet 35 conveyed on the belt. Thereby, wash water, which is deposited on the paper sheet 35 when washed in the washing bath 54, is removed. The dried paper sheet (the photographic print) 35 is conveyed to the passage changing section 48 which is disposed above the drying section 47 (see FIG. 1).

The passage changing section 48 conveys the paper sheet 35 of the normal size, which is conveyed in parallel, to the rearranging section 49. When the paper sheet 35 of the large size is conveyed, the passage changing section 48 switches the passage to a tray 60 disposed in a downstream of a sub-passage 24 a.

The rearranging section 49 rearranges the paper sheet 35 of the normal size conveyed in parallel to the single line. The rearranging section 49 is set in a replaceable manner according to the processing capacity of the photographic printing system 10. For instance, the rearranging section 49 is replaced with the one with faster rearranging speed, the one which does not perform rearranging or the like according to the photographic printing system 10. The sorter 50 outputs the plural paper sheet 35 conveyed from the rearranging section 49 in each print job.

As shown in FIG. 2, The flat roller 56 and the projection roller 57 are rotatably retained in the paper conveying rack 55 through bearing sections 63 respectively. A drive motor is connected to one of the above two rollers, a flat roller 56 for instance, through a drive transmission mechanism (not shown), rotating the flat roller 56 at a predetermined rotation speed according to the conveying speed of the paper sheet 35.

The flat roller 56 is constituted of a roller shaft 65 and a rubber roll 66 attached to the roller shaft 65. The roller shaft 65 is rotatably retained in the paper conveying rack 55 through the bearing section 63. The roller shaft 65 can be formed of any metal or resin material as long as the material is chemical-resistant (corrosion-resistant) to the developing solution 52 a, the bleaching-fixing solution 53 a and the washing solution 54 a. Further, a width of the rubber roll 66 is longer than that of the passage along which the paper sheet 35 is conveyed in parallel. The rubber roll 66 can also be formed of any resin material as long as the material is chemical-resistant to the developing solution 52 a, the bleaching-fixing solution 53 a and the washing solution 54 a. In the embodiment, the roller shaft 65 is formed of SUS 316, and the rubber roll 66 is formed of a silicone rubber, for instance.

The projection roller 57 has a skewer-like shape. The projection roller 57 is constituted of a roller shaft 68, roller pieces 70, pins 71 (see FIG. 7) and an E-ring 72. The roller shaft 68 is rotatably retained in the paper conveying rack 55 through the bearing section 63. The roller pieces 70, each of which is formed with projections 69 on an outer peripheral surface thereof, are attached and fixed to the outer circumferential surface the roller shaft 68. The pins 71 fix the roller pieces 70 on the roller shaft 68 which will be described later.

In the embodiment, the projection roller 57 is formed in the skewer-like shape by fixing the roller pieces 70 to the roller shaft 68 at certain intervals. However, the projection roller 57 can be formed in other configurations. For instance, a length of the roller piece 70 is extended in the width direction so that the projection roller 57 may have a similar shape to the flat roller 56. However, in that case, an outer diameter (a length from a shaft center of the roller shaft 68 to an outer circumferential surface of an elastic layer 79 which will be described later) may vary in an axial direction of the roller shaft 68. For that reason, it is preferable to form a roller piece 70 with a short width and fix plural roller pieces 70 to the roller shaft 68. The number of the roller pieces 70 to be fixed to the roller shaft 68 is not particularly limited, and may be arbitrarily increased or decreased according to the width of the paper sheet 35 to be conveyed.

As with the roller shaft 65, the roller shaft 68 is formed of any metal or resin material with the chemical resistance to the developing solution 52 a, the bleaching-fixing solution 53 a and the washing solution 54 a. In the embodiment, the roller shaft 68 is formed of SUS 316. The roller shaft 68 has pin holes 74 (see FIG. 7) for attaching the pins 71, which will be described later, and a ring groove 75 (see FIG. 7) for attaching the E-ring 72 in the corresponding fixing position of each roller piece 70.

As shown in FIGS. 3-5, the roller piece 70 is constituted of a circular core 78, the elastic layer 79 and a primer layer 80. The core 78 has an approximately ring (cylindrical) shape in which a fitting hole 77 is formed for attaching the core 78 to the roller shaft 68. The elastic layer 79, which has the projections 69 in a predetermined arrangement on the surface, is formed by coating molding on the outer peripheral surface of the core 78. The primer layer 80 adheres the elastic layer 79 and the core 78. Further, a note C in FIG. 5 indicates a rotation center line of the roller shaft 68.

The core 78 is formed of a coating section 78 a, on which the elastic layer 79 is coated and formed, and a spacer section 78 b which restricts a movement of the roller piece 70 in an axial direction of the roller shaft 68 (in a direction of the rotation center line C) when attaching the roller piece 70 to the roller shaft 68. The core 78 is formed of a so-called injection molding in which heated and melted resin material (modified polyphenylene ether) is injected, cooled and solidified in a mold (not shown). At that time, gas generated by the injection molding may be deposited on the outer peripheral surface of the core 78. The deposited gas weakens the adhesive strength between the outer peripheral surface of the core 76 and the primer layer 80 which will be described later. Accordingly, the adhesive strength between the elastic layer 79 and the outer peripheral surface of the core 76 is reduced. To prevent the reduction of the adhesive strength, it is preferable to perform a blasting on the surface of the coating section 78 a of the core 78 before forming the elastic layer 79 by coating molding. The blasting makes the outer peripheral surface of the core 78 rough and increases an adhesive area thereof. Accordingly, the adhesive strength is improved.

The resin material for forming the core 78 should have the chemical resistance to the developing solution 52 a, the bleaching-fixing solution 53 a and the washing solution 54 a, and heat resistance for preventing deformations and a secondary shrinkage which may be caused by the heat which is generated when the elastic layer 79 is formed by coating molding. In the embodiment, VESTORAN (produced by Daicel Degussa, Ltd.) is used as the resin material.

Further, in the embodiment, when the core 78 is formed by the injection molding, a pin groove 82, in which the pin 71 is engaged, is formed in an opening 77 a which is formed in a left edge portion of the fitting hole 77 (see FIGS. 4 and 5). By adjusting the depth of the pin groove 82 (which is a length in the direction of the rotation center line C), a fixing position of the roller piece 70 is adjusted with respect to the roller shaft 68. In the embodiment, the two pin grooves 82 are formed at diametrically opposed positions with respect to a center of the opening 77 a. However, the position of the pin groove 82 is not particularly limited, and can be changed as necessary.

Since the projections 69 are formed on the outer peripheral surface of the elastic layer 79, it is preferable that the elastic layer 79 is formed of a vulcanized rubber or the like which is chemical-resistant to the developing solution 52 a, the bleaching-fixing solution 53 a and the washing solution 54 a and whose hardness is not so high. In the embodiment, the elastic layer 79 is formed of the silicone rubber (produced by Dow Corning Toray Co., Ltd.) with the hardness of about 50 degrees. The projections 69 on the outer peripheral surface of the elastic layer 79 is also formed of the soft silicone rubber so that it becomes possible to prevent projection marks on the paper sheet 35 caused by deformation of the projections 69 when the paper sheet 35 is nipped between the flat roller 56 and the projection roller 57.

In the embodiment, each projection 69 is aligned in the direction of the rotation center line C to form a projection line. The projection line is arranged at a constant pitch in a circumferential direction of the elastic layer 79. Adjacent projection lines in the circumferential direction are staggered with respect to the rotation center line C to form a zigzag. Thereby, it becomes possible to prevent the projection marks on the leading end of the paper sheet 35 caused by the projections 69 partly pressing the paper sheet 35, which will be described later. Further, it becomes possible to keep the contact condition and the contact pressure of the paper sheet 35 constant. The arrangement pattern of the projections 69 is not limited to the examples shown in FIGS. 3-5. The projections 69 can be arranged in any arbitrary pattern which enables to prevent projection marks and keep the contact condition and the contact pressure constant.

Further, in the embodiment, the shape and the height of each projection 69 are adjusted in such a way that the projections 69, which are in the position for nipping the paper sheet 35, are deformed, and the projections 69, which are not in the position for nipping the paper sheet 35, contact the flat roller 56 (see FIG. 2). Thereby, it becomes possible to nip the paper sheet 35 with the constant contact pressure in the width direction so that the skew and the like are prevented.

The elastic layer 79 is formed by coating molding on the outer peripheral surface of the coating section 78 a of the core 78 as described above, and adhered to the outer peripheral surface of the coating section 78 a through the primer layer 80. In the embodiment, the blasting is performed to the core 78 which is formed by the injection molding. Thereafter, the primer is coated to the coating section 78 a to form the primer layer 80. The primer layer 80 is formed of a silicone-based primer (produced by Shin-Etsu Silicone, Ltd.) which is chemical-resistant. The core 78, which is formed with the primer layer 80, is set as a core in a mold 84 for forming the elastic layer as shown in FIG. 6, for instance.

In FIG. 6, the mold 84 is constituted of a top mold 86, which is formed to cover an upper half of the core 78, a bottom mold 87, which is formed to cover a lower half of the core 78, and a positioning block 88 for positioning the core 78. The top mold 86 and the bottom mold 87 are joined at a mold parting line PL in a detachable manner. In the top and the bottom molds 86 and 87, mold faces 89 a and 89 b, which correspond to the shape of the core 78, are formed respectively. A cavity 90 is formed between the mold faces 89 a, 89 b and the coating sections 78 a of the core 78 respectively according to a thickness of the elastic layer 79. Hollows 90 a, which correspond to the shape and the arrangement of the projections 69, are formed in areas in the mold faces 89 a and 89 b on the opposite side of the coating section 78 a. An injection hole 91 is formed through the top mold 86 for injecting the heated and melted silicone rubber into the cavity 90. Further, openings 92 a and 92 b are formed in the top and bottom molds 86 and 87 respectively. The positioning block 88 is set in the openings 92 a and 92 b when the top and bottom molds 86 and 87 are joined.

The positioning block 88 is formed in a shape to be fitted in the pin groove 82 formed in the opening 77 a of the core 78. To set the core 78 coated with the primer layer 80 in the mold 84, the positioning block 88 is fit in the pin groove 82 first. Then, the positioning block 88 and the core 78 are set in the bottom mold 87. Thereafter, the top mold 86 and the bottom mold 87 are joined. Thus, the core 78 is set in the mold 84 in such a way that the pin groove 82 is set in the predetermined direction, that is, the core 78 is positioned in the same position in the circumferential direction. Thereby, the phase of the arrangement of the projections 69 formed on the outer peripheral surface of each roller piece 70 is automatically aligned when the roller pieces 70 are attached to the roller shaft 68, which will be described later.

After setting the core 78 in the mold 84, the heated and the melted silicone rubber is injected through the injection hole 91. Thereafter, the silicone rubber is cooled and solidified to form the elastic layer 79 on the coating section 78 a of the core 78. Thus the roller piece 70 is formed. The outer peripheral surface of the coating section 78 a and the elastic layer 79 are adhered through the primer layer 80 by the heat generated by forming of the elastic layer 79 by coating molding. When the silicone rubber is solidified, the top and the bottom molds 86 and 87 are separated, the roller piece 70 is taken out from the mold 84 and the flash and the like are removed. Even if there is PL flash on the tips of the projections 69 caused by the PL between the top and the bottom molds 86 and 87, such PL flash has little effect on the paper sheet 35, since the projections 69 are deformed while conveying the paper sheet 35. In the embodiment, the mold 84 is constituted of the top and the bottom molds 86 and 87. However, to facilitate the separation of the molds, the mold 84 may be configured with four or more molds by further dividing the top and the bottom molds 86 and 87.

Thus, when producing the roller piece 70, the primer layer 80, which is chemical-resistant, is formed on the coating section 78 a on the core 78, and the elastic layer 79 is formed on the primer layer 80. Thereby, the core 78 and the elastic layer 79 are adhered and integrated through the primer layer 80. Accordingly, the tightening force of the elastic layer 79 is prevented from relaxing due to swelling and stretching caused by the stress at the conveyance unlike the projection tubes. As a result, the slipping of the elastic layer 79 is prevented when conveying the paper sheet 35. Further, since the core 78 and the elastic layer 79 are not directly adhered by the chemical bond, but through the primer layer 80, the uniform adhesive strength is secured regardless of the surface condition of the coating section 78 a of the core 78.

Although processes to form the elastic layer 79 by coating molding on the core 78 are necessary in the embodiment, the conventional processes, in which the core 78 is inserted into the projection tube (not shown), are omitted. Accordingly, the working efficiency is significantly improved. Further, since each projection 69 is arranged in the designed position by integrally forming the elastic layer 79 and the core 78, it becomes possible to prevent the deviations of the projections 69 from the designed positions occurred in the above conventional processes.

After forming the predetermined number of roller pieces 70, each roller piece 70 is attached to the roller shaft 68 one by one. Hereinafter, referring to FIGS. 7A-7C, processes for attaching the roller pieces 70 to the roller shaft 68 are described. The roller piece 70 is attached to the roller shaft 68 one by one from a right end of the roller shaft 68.

Before attaching the first roller piece 70, a first pin 71 is engaged in the pin hole 74 formed on the left end side of the roller shaft 68 as shown in FIG. 7A. Then, the roller piece 70 is attached to the roller shaft 68 by inserting the right end of the roller shaft 68 into the fitting hole 77 (see FIGS. 4 and 5) of the roller piece 70. Thereafter, the roller piece 70 is slid to the left along the roller shaft 68 until the pin 71 is engaged in the pin groove 82. The pin 71 restrains further slide movement and the rotation of the roller piece 70 in the circumferential direction.

When the slide movement of the first roller piece 70 is completed, the second pin 71 is engaged in the second pin hole 74, and the second roller piece 70 is attached to the right end of the roller shaft 68. Then, the second roller piece 70 is slid to the left along the roller shaft 68 until the second pin 71 is engaged in the second pin groove 82 in the same manner as the first roller piece 70. Thereby, the first pin 71 and the second roller piece 70 restrain the movement of the first roller piece 70 in the axial direction (the direction of the rotation center line C) of the roller shaft 68, and thus the first roller piece 70 is fixed to the roller shaft 68. Hereinafter, the roller piece 70 is fixed to the roller shaft 68 one by one in the same manner.

As shown in FIG. 7C, when the last roller piece 70 is attached to the roller shaft 68 and completely slid, the E-ring 72 is engaged in the ring groove 75. Thereby, the movements of all the roller pieces 70 in the direction of the rotation center line C (see FIG. 5) are restrained. Further, as described above, since the rotation of each roller piece 70 is restrained in the circumferential direction by using the pin 71, all roller pieces 70 are completely fixed to the roller shaft 68.

In the embodiment, the core 78 is placed in the mold 84 in the predetermined position in the circumferential direction when the elastic layer 79 is formed by coating molding on the core 78. Therefore, the phase of the arrangement of the projections 69 on each roller piece 70 is automatically aligned only by engaging the pin 71 in the pin groove 82. Further, in the embodiment, the projections 69 on each roller piece 70 is formed in such a way that the projection lines, in which the projections 69 are aligned in the direction of the rotation center line C of the core 78, are arranged in the zigzag with the constant pitch in the circumferential direction of the elastic layer 79. Accordingly, it becomes possible to keep the entry angle constant throughout the leading end of the paper sheet 35 when the paper sheet 35 enters between the flat roller 56 and the projection roller 57. Further, the contact condition and the contact pressure between the paper sheet 35 and the projection roller 57 are kept constant throughout the paper sheet 35 in the width direction.

Next, the operation of the photographic print system 10 of the above configuration is described. As shown in FIG. 1, when the user issues a print command, the controller 15 pulls out the predetermined length of the photosensitive recording paper 25 from the magazines 27 a and 27 b loaded in the supply section 17, and drives the cutters 30 a and 30 b to cut the paper sheet 35. In the back-printing section 18, the predetermined information such as the photography information is recorded on the paper sheet 35. Then, in the skew-correcting section 19, the skew of the paper sheet 35 is corrected. Thereafter, the paper sheet 35 is conveyed to the exposure section 20. In the exposure section 20, the image is scanned and exposed on the paper sheet 35 by the laser light (the recording light) which is modulated according to the image data.

After the exposure, the paper sheet 35 is conveyed to the sorter section 22 through the receiver section 21. When the paper sheet 35 is of the normal or small size, the sorter section 22 sorts the paper sheet 35 into two lines. When the paper sheet 35 is of the large size, which cannot be conveyed in parallel, the sorter section 22 conveys the paper sheet 35 in the single line without sorting. In the embodiment, the paper sheet 35 of the normal size is used. After being sorted into two lines, the paper sheet 35 is conveyed to the processor 14 through the carrying section 23.

In the processor 14, the paper sheet 35 is subject to processing such as developing, fixing and washing in this order through baths 52-54 respectively, while being nipped and conveyed by the conveying roller pair 58, which is constituted of the flat roller 56 and the projection roller 57, disposed in each bath 52-54. In the embodiment, each roller piece 70, which is to be attached to the roller shaft 68 of the projection roller 57, is formed by coating the elastic layer 79 on the core 78 through the primer layer 80. As a result, the slipping of the roller piece 70, which is caused by the stress relaxation or slight swelling of the elastic layer 79 in the processing solution, are prevented when the paper sheet 35 is conveyed. Accordingly, the failures in conveying the paper sheet 35 are prevented. Further, the uniform adhesive strength is secured regardless of the surface condition of the coating section 78 a of the core 78.

Further, the processes for producing the roller piece 70 are increased since the elastic layer 79 is formed by coating molding on the core 78. However, the working efficiency is substantially improved since the processes for inserting the core 78 into the projection tube (not shown) become unnecessary. Furthermore, since the core 78 is no longer inserted into the projection tube (not shown) by manual work, the tearing of the projection tube caused by inserting the core 78 into the projection tube, or the variations in the outer diameter of each roller piece 70 in the direction of rotation center line C are prevented. Thus, yields in manufacturing the projection roller 57 and the quality stability are improved at the same time.

In the embodiment, each projection 69 is aligned to form projection lines in the direction of the rotation center line C. The projection lines are arranged at the constant pitch in the zigzag. Further, the projections 69 of each roller piece 70 attached to the roller shaft 68 are phase-coherent. Accordingly, the entry angle of the leading end of the paper sheet 35 between the projection rollers 56 and 57 of the conveying roller pair 58 can be kept constant throughout the leading end of the paper sheet 35. Thereby, the projection marks, which are caused by partly pressing the leading end of the paper sheet 35 by the projections 69, are prevented. Further, since the contact condition and the contact pressure between the paper sheet 35 and the projection roller 57 are kept constant throughout the width direction of the paper sheet 35, the unbalance in the conveying force of the conveying roller 58 and the changes in the roll alignment are restricted. Accordingly, the skew of the paper sheet 35 is prevented.

After being developed, fixed and washed in the baths 52-54, the paper sheet 35 is conveyed to the drying section 47. In the drying section 47, the dried air heated by the heater is supplied to the paper sheet 35 to remove the wash water deposited on the paper sheet 35. The dried paper sheet 35 is conveyed to the passage changing section 48. Since the paper sheet 35, which is conveyed in parallel, is of the normal size, the passage changing section 48 conveys the paper sheet 35 to the rearranging section 49. The rearranging section 49 rearranges the parallel conveying line into the single line and conveys the paper sheet 35 to the sorter 50. The sorter 50 outputs the plural paper sheets 35 conveyed from the rearranging section 49 according to each print job.

In the embodiment, the core 78 is formed of the modified polyphenylene ether which is the thermoplastic resin. However, other material, which is chemical- and heat-resistant, can be used for forming the core 78. For instance, as shown in Table 1 below, the core 78 can be formed of one of polyamide, polyphenylene sulfide or polypropylene, or a copolymer copolymerized from at least two of the above materials. Further, the core 78 can be formed of thermosetting resin such as phenol, or metal material such as SUS316, titanium, hastelloy and inconel. When the metal material is used for forming the core 78, the roller shaft 68 and the core 78 can be formed integrally by forming steps in the roller shaft 68. When the core 78 and the roller shaft 68 are separately formed, it is preferable to form the core 78 by cutting processing, metal injection molding (MIM) or lost-wax molding.

In the embodiment, the elastic layer 79 is formed of the vulcanized rubber (the silicone rubber). However, it is possible to use other chemical-resistant material for forming the elastic layer 79, such as hydrogenated styrenic thermoplastic elastomer or olefinic thermoplastic elastomer with the hardness of approximately 50 degrees as shown in Table 1 below.

In the embodiment, the core 78 and the elastic layer 79 are adhered through the primer layer 80. However, the present invention is not limited to the embodiment. For instance, as shown in the Table 1 below, when the core 78 is formed of the modified polyphenylene ether, which is the thermoplastic resin, and the elastic layer 79 is formed of the silicone rubber, the core 78 and the elastic layer 79 are directly adhered through the chemical bond at an interface between the thermoplastic resin and the silicone rubber caused by coating the elastic layer 79 on the peripheral surface of the core 78 without the use of the primer layer 80.

Further, when the elastic layer 79 is formed by the thermoplastic elastomer, which has good adherence to the core 78 formed of the thermoplastic resin, it is also possible to directly adhere the core 78 and the elastic layer 79 through the chemical bond without the use of the primer layer 80. For instance, as shown in FIG. 1, when the core 78 is formed of the modified polyphenylene ether, and the elastic layer 79 is formed of the hydrogenated styrenic thermoplastic elastomer, the core 78 and the elastic layer 79 are directly adhered since the styrene component in both materials are melted. Further, when the core 78 is formed of the polypropylene, and the elastic layer 79 is formed of the olefinic thermoplastic elastomer, the core 78 and the elastic layer 79 are directly adhered since the polypropylene component in both materials are melted. TABLE 1 Type of Core Elastic layer joint Thermo- Polyamide Silicone Primer plastic rubber Resin Modified Silicone Primer polyphenylene rubber Chemical ether bond Hydrogenated Chemical styrenic Bond thermoplastic elastomer Polyphenylene Silicone Primer Sulfide rubber polypropylene Silicone Primer rubber Olefinic Chemical thermoplastic bond elastomer Thermo- Phenol Silicone Primer Setting Rubber Resin Metal SUS316 Silicone Primer material Titanium Rubber Hastelloy Inconel

In the embodiment, the circumferential rotation of the roller piece 70 is prevented by forming the pin groove 82 in each roller piece 70 (the core 78) and engaging the pin 71, which is attached to the roller shaft 68, in the pin groove 82. However, the present invention is not limited to the embodiment. It is also possible to prevent the circumferential rotation of the roller piece 96, for instance, by using a roller shaft 95 with a D-shaped section instead of the roller shaft 68 (see FIG. 8A), and forming a D-shaped fitting hole 97 through a roller piece 96 instead of the fitting hole 77 (see FIG. 8B). In that case, to prevent the slide movement of the roller piece 96 in the direction of the rotation center line C, the ring groove 75 for attaching 15 the E-ring 72 is formed in a position corresponding to the attaching position of the roller piece 96. Since the roller pieces 96 and 70 have the same configuration except for the shape of the fitting hole 97, the same numeral is assigned to the same member and the explanation is omitted.

To attach the roller piece 96 to the roller shaft 95, the first E-ring 72 is attached to the ring-groove 75 on the left end side of the roller shaft 95 as shown in FIG. 9 before attaching the first roller piece 96. Next, the right end section of the roller shaft 95 is inserted into the fitting hole 97 of the roller piece 96, and the roller piece 96 is slid to the left along the roller shaft 95 until the roller piece 96 is stopped by the E-ring 72. When the first roller piece 96 is completely slid and stopped, as shown in FIG. 9B, the second E-ring 72 is attached to the second ring-groove 75, which is second from the left, to prevent the slide movement of the first roller piece 96 in the direction of the rotation center line C. The same is applied to the third roller piece 96 and after. As the slide movement in the direction of the rotation centerline C and the circumferential rotation of each roller piece 96 are restrained by the E-rings 72 and the roller shaft 95, all the roller pieces 96 are completely fixed to the roller shaft 95.

Further, for instance, as shown in FIG. 10A, a roller shaft 100, in which plural first key grooves 99 (see FIG. 11) for attaching keys 98 are formed in positions corresponding to attaching positions of roller pieces 101, can be used. As shown in FIG. 10B, a second key groove 102 can be formed in the opening 77 a of the fitting hole 77 through the roller piece 101. Since the roller pieces 101 and 70 have the same configuration except for the second key groove 102, the same numeral is assigned to the same member and the explanation is omitted.

To attach the roller piece 101 to the roller shaft 100, as shown in FIG. 11A, the first key 98 is attached to the first key groove 99 on the left end side of the roller shaft 100 before attaching the first roller piece 101. Next, the right end section of the roller shaft 100 is inserted into the fitting hole 77 of the first roller piece 101, and the roller piece 101 is slid to the left along the roller shaft 100 until the roller piece 101 is stopped by engaging the key 98 in the second key groove 102. Thereafter, as shown in FIG. 11B, the slide movement of the roller piece 101 in the axial direction is prevented by attaching the second key 98 to the second key groove 99 which is second from the left. The same is applied to the third roller piece 101 and after. When the last roller piece 101 is attached to the roller shaft 100, the E-ring 72 (not shown) is attached to the right end of the roller piece 101. The slide movement in the direction of the rotation center line C and the circumferential rotation of each roller piece 101 are prevented by using the key 98 and the second key groove 102. Thus, all the roller pieces 101 are completely fixed to the roller shaft 100.

Further, as shown in FIGS. 12A and 12B, a convex section 104 is formed on one side of the core 78 of a roller piece 103, for instance, on the left side, and a concave section 105 is formed on the other side, in this case, on the right side. The convex section 104 and the concave section 105 of the adjacent roller pieces 103 engage with each other. In that case, before attaching the first roller piece 103, a stopper 107 formed with the concave section 105 is fixed to the left end of a roller shaft 106 by a screw 108 and the like as shown in FIG. 12A. Next, the right end of the roller shaft 106 is inserted into the fitting hole (not shown) of the roller piece 10.3, and the roller piece 103 is slid to the left along the roller shaft 106 until the roller piece 103 is stopped by engaging the convex section 104 in the concave section 105 of the stopper 107.

When the first roller piece 103 is completely slid and stopped, the second roller piece 103 and after are attached in the same manner to engage the convex section 104 in the concave section 105 of the previously attached roller piece 103. When the last roller piece 103 is attached, a stopper 109 formed with the convex section 104 is attached and fixed to the right end side of the roller piece 103. The slide movement of each roller piece 103 in the direction of the rotation center line C and the circumferential rotation of each roller piece 103 is restrained by the stoppers 107 and 109. Thus, all the roller pieces 103 are completely fixed to the roller shaft 106.

In the embodiment, the projection roller 57 (the conveying roller pair 58) are disposed in each bath 52-54. However, the present invention is not limited to the embodiment. The projection roller 57 can be disposed in arbitrary areas along the main passage 24 and the sub passage 24 a, or in each section constituting the photographic printing system 10. Further, the present invention is not limited to the projection roller 57 used in the photographic printing system 10. It is also possible to use the projection roller in various conveying roller pairs for conveying various sheets such as thin metal sheet, paper, film and the like.

Although the present invention has been described with respect to the preferred embodiment, the present invention is not to be limited to the above embodiment but, on the contrary, various modifications will be possible to those skilled in the art without departing from the scope of claims appended hereto. 

1. A conveying roller comprising: a roller shaft; and plural cores fixed to said roller shaft, said cores and said roller shaft integrally rotating about a rotation center line of said roller shaft, an elastic layer having plural projections being formed by coating molding on an outer peripheral surface of each of said cores.
 2. A conveying roller according to claim 1, wherein said elastic layer is formed after forming a primer layer on each of said cores by coating a primer.
 3. A conveying roller according to claim 2, wherein a blasting is performed to a surface of each of said cores for increasing adhesive strength before forming said primer layer.
 4. A conveying roller according to claim 1, wherein said plural projections are aligned to form projection lines, which are in parallel to said rotation center line, said projection lines are arranged at a constant pitch in a circumferential direction.
 5. A conveying roller according to claim 4, wherein said plural projections are arranged in a zigzag by shifting said adjacent projection lines in the direction of said rotation center line.
 6. A conveying roller according to claim 1, wherein a fitting hole is formed through each of said cores along said rotation center line, each of said cores is attached to said roller shaft by inserting said roller shaft into said fitting hole.
 7. A conveying roller according to claim 6, wherein a fixing member is attached to said roller shaft for fixing each of said cores to said roller shaft.
 8. A conveying roller according to claim 7, wherein an engaging section, in which said fixing member is engaged, is formed in each of said cores for fixing each of said cores to said roller shaft.
 9. A method for producing a conveying roller comprising the steps of: forming an elastic layer having plural projections by coating molding on an outer peripheral surface of each of plural cores; and fixing said cores, each of which is formed with said elastic layer, to a roller shaft such that said cores and said roller shaft integrally rotate about a rotation center line of said roller shaft.
 10. A method according to claim 9, wherein said coating molding of said elastic layer is performed by setting said core as a core in a mold, and filling an elastic material in a cavity formed between said core and said mold.
 11. A method according to claim 10, wherein said coating molding of said elastic layer is performed after a primer layer is formed on each of said cores by coating a primer.
 12. A method according to claim 11, wherein a blasting is performed to a surface of each of said cores for increasing adhesive strength before forming said primer layer.
 13. A method according to claim 10, wherein said core is set in said mold in a predetermined position in a circumferential direction.
 14. A method according to claim 13, wherein said plural projections are aligned to form projection lines, which are in parallel to said rotation center line, said projection lines are arranged at a constant pitch in said circumferential direction.
 15. A method according to claim 14, wherein said plural projections are arranged in a zigzag by shifting said adjacent projection lines in the direction of said rotation center line.
 16. A method according to claim 9, wherein a fitting hole is formed through each of said cores along said rotation center line, each of said cores is attached to said roller shaft by inserting said roller shaft into said fitting hole.
 17. A method according to claim 16, wherein a fixing member is attached to said roller shaft for fixing each of said cores to said roller shaft.
 18. A method according to claim 17, wherein an engaging section, in which said fixing member is engaged, is formed in each of said cores for fixing said cores to said roller shaft.
 19. A method according to claim 9, wherein said core is formed of a thermoplastic resin material, a thermosetting resin material or a metal material.
 20. A method according to claim 9, wherein said elastic layer is formed of a vulcanized rubber or a thermoplastic elastomer.
 21. A method according to claim 20, wherein a hardness of said elastic layer is approximately 50 degrees.
 22. A conveying apparatus comprising: a conveying roller pair including: a conveying roller formed such that plural cores are attached to a roller shaft, said cores and said roller shaft integrally rotating about a rotation center line of said roller shaft, an elastic layer having plural projections being formed by coating molding on an outer peripheral surface of each of said cores; and a flat roller used in a pair with said conveying roller for nipping and conveying a sheet.
 23. A conveying apparatus according to claim 22, wherein said elastic layer is formed after forming a primer layer on each of said cores by coating a primer.
 24. A conveying apparatus according to claim 22, wherein said projections in a nip area, where said sheet is nipped, are deformed so that said projections outside said nip area in a width direction of said conveying roller contact said flat roller when said conveying roller and said flat roller nip said sheet.
 25. A conveying apparatus according to claim 24, wherein a hardness of said elastic layer is approximately 50 degrees.
 26. A conveying apparatus according to claim 22, wherein said sheet is a photosensitive material.
 27. A conveying apparatus according to claim 22, wherein said conveying roller pair is disposed in a storage tank in which a processing solution is stored, and said elastic layer, said cores and said primer layer are chemical-resistant to said processing solution. 